"Canada, which has a disputed sovereignty claim to the Northwest Passage, will require all larger ships plying the Arctic sea route to register starting on July 1, the government said on Tuesday.

Officials said the requirement will help the government better protect the region's fragile environment, but the move is also designed to back Ottawa's view that Canada has sole legal authority over the fabled sea link across the top of North America, between the Atlantic and Pacific.

Ottawa considers the Northwest Passage an internal waterway under its jurisdiction, but the United States and some European countries consider the passage an international waterway."